This project investigates the longevity of Drosophila species in relation to the phylogeny, distribution and adaptations to seasonal change. Emphasis is on species of the virilis group, for which cytological relationships are known, and on somewhat more distant relatives for which general phylogenetic relationships have been established. Flies are characterized by the responses of developmental stages and adults to temperature and day length. Longevities are measured under a variety of conditions. From these data protocols are developed to achieve the immediate practical end of placing adults of certain species of Drosophila into cold storage. Information is also obtained to use in further work directed toward formulating methods to alter longevities of other species and designing methods eventually for placing any species of Drosophila into long-term storage. Information to be gained also permits identification of species which have evolved true increases in longevity, allowing us to focus attention on these forms, ask by what mechanisms (genetic, physiological, molecular) longevity) longevity increases have actually been achieved, and so advance both our theoretical and practical understanding of longevity and aging.